CN110250146B - Fruit tree profiling spraying machine and method based on laser detection and image processing technology - Google Patents

Abstract

The invention belongs to the field of orchard profiling spraying, and particularly relates to a fruit tree profiling spraying machine and method based on laser detection and image processing technologies. The fruit tree profiling sprayer comprises a vehicle body chassis, a pesticide application device, an image acquisition device, a laser detection device and a data processing control system. According to the invention, different profiling spraying modes are selected according to the death and disease rates of fruit trees in the orchard. When the death rate and the disease rate of fruit trees in the orchard are low, a real-time profiling spraying mode is selected; when the death rate and the disease rate of fruit trees in the orchard are higher, a centering profiling spraying mode is selected. The invention has low profiling cost, realizes variable detection and can improve the profiling accuracy.

Description

Fruit tree profiling spraying machine and method based on laser detection and image processing technology

Technical Field

The invention belongs to the field of orchard profiling spraying, and particularly relates to a fruit tree profiling spraying machine and method based on laser detection and image processing technologies.

Background

The idea of profiling spraying is to adjust the pesticide application parameters in real time according to the canopy characteristics of the target crops. In order to obtain the characteristics of the target canopy, a canopy detection technology based on a sensor is widely applied as an important means for obtaining canopy information, wherein the laser sensor has the advantages of high precision and strong anti-interference capability, and the distance from the end face of the sensor to the surface of a fruit tree is measured in a non-contact measurement mode so as to detect the outline of the target.

In orchard variable spraying technology current research and prospect analysis, it is pointed out that in the prior art, a multifunctional LIDAR sensor can be used for accurately detecting a fruit tree structure, but documents indicate that the LIDAR sensor is high in price, large in data processing amount in the using process and high in total cost of use. In addition, according to the flight time of the laser from the emitting point to the receiving point after being reflected by the target, the array type ultrasonic sensor can also realize the profiling of the fruit tree. However, the ultrasonic sensor measurement method requires that the sensors arranged in an array cover the whole object to be measured, and the arrangement mode has the following problems in practical application: firstly, the resolution and the measurement precision of the ultrasonic sensor are low; secondly, when the strip-shaped arrangement mode is used for measurement, the small vibration at the bottom can easily cause a large measurement error of the top end sensor, the size is large, and the installation and transportation are not easy; thirdly, for different kinds of fruit trees with different growth periods, the density of the canopy of the tree is different, and under the condition that the canopy is relatively sparse, the signal loss rate of the sensor is high, and the measurement accuracy is reduced. Under the sparse condition, the signal loss rate of the sensor is high, and the accuracy of measuring the volume of the canopy is reduced. Fourthly, fruit trees with serious diseases and death phenomena often exist in the orchard, the fruit trees needing to be replanted do not need to be subjected to pesticide application operation, and if the damaged fruit trees are continuously sprayed, the waste of liquid medicine and the environmental pollution are caused.

Disclosure of Invention

The invention aims to provide a fruit tree profiling sprayer based on laser detection and image processing technology, which only adopts two laser sensors to reduce profiling cost; the laser detection device is small in size and convenient to transport; the canopy characteristic acquisition based on image processing realizes variable detection and can improve the profiling accuracy.

Another purpose of the invention is to provide a fruit tree profiling spraying method based on laser detection and image processing technology, which considers the crown layer sparsity characteristic and the fruit tree death and disease phenomena, and considers the influence of the crown layer density characteristic on the return of laser signals and the application amount: according to the fruit tree sparsity condition, detection parameters (laser sensor movement time interval, laser sensor movement speed) and target parameters (canopy volume, canopy height and air volume) are adjusted in a self-adaptive mode, so that spraying parameters are changed, and profiling pesticide application efficiency is improved. In addition, the phenomenon that fruit trees have high fruit tree damage rate in an orchard is considered, spraying is decided according to the detected target parameters, and the increase of pesticide application cost and the waste of environment are avoided.

In order to achieve the purpose, the invention provides the following technical scheme:

a fruit tree profiling sprayer based on laser detection and image processing technology comprises a vehicle body chassis 28 and a pesticide applying device, wherein the pesticide applying device comprises a pesticide box 30, a flow pump 17, a fan 18, a left spray nozzle 25 and a right spray nozzle 12, a liquid outlet of the pesticide box 30 is sequentially connected with the flow pump 17 and the fan 18 through pipelines, and a left air outlet pipe and a right air outlet pipe of the fan 18 are respectively connected with the left spray nozzle 25 and the right spray nozzle 12 through a left fluid pipeline 16 and a right fluid pipeline 13.

A speed sensor 29 for acquiring the operation speed of the machine tool is arranged on the vehicle body chassis 28;

the pesticide applying device further comprises a spray head up-and-down moving swing device; the left nozzle 25 and the right nozzle 12 are respectively arranged at the left side and the right side of the rear part of the vehicle body chassis 28 through the nozzle up-down moving and swinging device;

the fruit tree profiling sprayer further comprises an image acquisition device, a laser detection device 6 and a data processing control system;

the image acquisition device comprises a camera mounting frame 4, a left camera 1 and a right camera 3, wherein the camera mounting frame 4 is vertically and fixedly connected to the front part of the vehicle body chassis 28, and the left camera 1 and the right camera 3 are respectively mounted on the left side and the right side of the camera mounting frame 4;

the laser detection device 6 comprises a laser detection mounting frame 7, a base 601, a motor mounting rod 602, a support 603, a laser wheel 606, a left laser sensor 614, a right laser sensor 605, a first rotating motor 607, a second rotating motor 611, a first connecting rod 613 and a second connecting rod 609;

the laser detection mounting rack 7 is vertically and fixedly connected to the middle part of the vehicle body chassis 28, and the base 601 is fixedly connected to the rear end face of the laser detection mounting rack 7;

the front ends of a pair of horizontal brackets 603 are respectively and vertically fixedly connected to the upper part and the lower part of the base 601, and the upper end and the lower end of a laser wheel 606 parallel to a vertical plane are respectively and fixedly connected with the rear ends of the two brackets 603; the motor mounting rod 602 is fixedly connected between the rear ends of the two brackets 603; the left laser sensor 614 and the right laser sensor 605 are respectively slidably arranged on the left half circumference and the right half circumference of the laser wheel 606 to respectively scan the fruit tree canopies on the left side and the right side;

the first rotating motor 607 and the second rotating motor 611 are concentrically and fixedly connected with the laser wheel 606 on the motor mounting rod 602 and the base 601 respectively; a power output shaft of the first rotating electric machine 607 is connected to the left laser sensor 614 through a first link 613, and a power output shaft of the second rotating electric machine 611 is connected to the right laser sensor 605 through a second link 609;

a first angle sensor 612 is arranged between the first rotating electric machine 607 and the first connecting rod 613, and a second angle sensor 610 is arranged between the second rotating electric machine 611 and the second connecting rod 609;

the data processing control system comprises an image data processing control module 2, a laser data processing control module 5 and a spray control module 27;

the image data processing control module 2 is installed on the camera installation frame 4, is connected with the left camera 1, the right camera 3, the laser data processing control module 5 and the spraying control module 27, receives and processes fruit tree canopy pictures acquired by the left camera 1 and the right camera 3, and sends processing results to the laser data processing control module 5 and the spraying control module 27;

the laser data processing control module 5 is installed on the laser detection installation frame 7 and is connected with the speed sensor 29, the first rotating motor 607, the second rotating motor 611, the left laser sensor 614, the right laser sensor 605, the first angle sensor 612, the second angle sensor 610 and the spray control module 27; the laser data processing control module 5 controls the start, stop and movement speed of the first rotating motor 607 and the second rotating motor 611 according to the tool operation speed returned by the speed sensor 29, the spacing distance between the camera mounting frame 4 and the laser detection mounting frame 7 and the processing result sent by the image data processing control module 2; receiving and processing data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610, and sending the processing result to the spray control module 27;

the spraying control module 27 is arranged on a vehicle body chassis 28 and is connected with a speed sensor 29, a flow pump 17 of the pesticide applying device, a fan 18, a left driving motor 21, a right driving motor 14, a left rotating motor 24 and a right rotating motor 11, and is used for calculating spraying requirements and spraying delay time according to processing results sent by the laser data processing control module 5 and machine tool operation speeds returned by the speed sensor 29, further adjusting the pesticide applying device according to the spraying requirements and starting spraying.

The rear ends of the two brackets 603 are respectively provided with a first limiting sheet 604 and a second limiting sheet 608 for limiting the displacement of the right laser sensor 605 and the left laser sensor 614.

The distance between the laser detection device 6 and the ground is 30-80 cm;

the spacing distance between the camera of the image acquisition device and the laser sensor of the laser detection device 6 is 0.5-1.5 m;

the spacing distance between the laser sensor of the laser detection device 6 and the spray head of the pesticide application device is 0.5-1.5 m.

And a left adjusting sheet 20 and a right adjusting sheet 19 for adjusting air volume are respectively arranged inside the left air outlet pipe and the right air outlet pipe of the fan 18.

The nozzle up-and-down moving swinging device comprises a left driving motor 21, a right driving motor 14, a left lead screw 22, a right lead screw 10, a left bracket 15, a right bracket 9, a left moving slide block 23, a right moving slide block 8, a left rotating motor 24 and a right rotating motor 11;

the left screw 22 and the left bracket 15 which are mutually parallel are vertically arranged at the left side of the rear part of the vehicle body chassis 28, and the right screw 10 and the right bracket 9 which are mutually parallel are vertically fixedly connected at the right side of the rear part of the vehicle body chassis 28; the left moving sliding block 23 is sleeved on the left screw rod 22 and the left support 15, and the right moving sliding block 8 is sleeved on the right screw rod 10 and the right support 9; the left driving motor 21 and the right driving motor 14 respectively drive the left lead screw 22 and the right lead screw 10 to rotate, so that the left moving slide block 23 and the right moving slide block 8 do vertical linear motion;

the left rotating motor 24 and the right rotating motor 11 are respectively and fixedly connected to the left moving slide block 23 and the right moving slide block 8; wherein, the rotating shaft of the left rotating motor 24 is connected with the left nozzle 25, and the rotating shaft of the right rotating motor 11 is connected with the right nozzle 12.

The left spray nozzle 25 and the right spray nozzle 12 adopt gas-liquid double-flow spray nozzles, and the spray nozzle bodies are provided with atomizing chambers; the left camera 1 and the right camera 3 are CCD cameras.

A fruit tree profiling method based on laser detection and image processing technology and utilizing the fruit tree profiling sprayer comprises a real-time profiling spraying mode and specifically comprises the following steps:

step 1: reading the position and row spacing data of the fruit tree, and collecting an image of the fruit tree;

the data processing control system reads the fruit tree position and planting row spacing L from the fruit tree planting database_{Line of}The sprayer operates along the middle position of two rows of fruit trees, and when the sprayer moves to a position corresponding to the position of the fruit trees, the image data processing control module 2 controls the left camera 1 and the right camera 3 to respectively collect fruit tree images on the left side and the right side;

step 2: calculating the porosity of the fruit tree canopy;

carrying out image segmentation and morphological processing on the collected fruit tree image to obtain a binary image only containing a fruit tree canopy, carrying out region filling on the binary image, then calculating the void ratio K of the fruit tree canopy through the following formula, and taking the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂The total pixel number of the pixel value of 1 in the binary image after the area filling;

and step 3: variable scanning is carried out, and the unit volume of the canopy of the fruit tree is obtained in real time;

the laser data processing control module 5 processes the machine tool working speed S returned by the speed sensor 29_{Spraying machine}And the spacing distance between the camera and the laser sensor, and calculating the delay time detected by the laser sensor; after the delay time, the laser data processing control module 5 respectively controls the first rotating motor 607 and the second rotating motor 611 to start at a certain rotating speed, and the laser data processing control module 5 respectively sets the left laser sensor 614 and the right laser sensor 605 to scan the angular velocity S according to the fruit tree canopy void ratio K at the left and right sides_{Laser wheel}Detecting fruit trees on the left side and the right side at different movement intervals; the movement interval time is the interval time between the completion of one semi-circular movement of the left laser sensor 614 or the right laser sensor 605 on the laser wheel 606 and the start of the next semi-circular movement; the laser data processing control module 5 calculates the volume of the fruit tree canopy units on the left side and the right side according to the data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610 by the following formula:

L_i'＝L_{line of}/2；

L₀＝(L_i+R)cosσ；

L＝L_i′-L₀；

H_n＝(L_i1+L_in+2R)×sinσ；

V_n＝H_n×2L×S_{Spraying machine}×T；

In the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀a horizontal projection connecting the center of the laser wheel and the length of the laser beam reaching the surface of the canopy;

L_{line of}Is the planting row spacing;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

S_{spraying machine}The operating speed of the machine tool;

t is the time length for the laser sensor to rotate for a half cycle;

V_nthe volume of the fruit tree canopy unit is detected in real time;

and 4, step 4: acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of a spray head;

the spray control module 27 responds to the tool operating speed S from the speed sensor 29_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time, the spray control module 27 controls the medicine application device to start working; the spraying control module 27 calculates the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H_n＝(L_i1+L_in+2R)×sinσ；

W_n＝P1+V_n；

Q＝V_n*q；

swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

r is the radius of the laser wheel;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

s_{spraying machine}The advancing speed of the sprayer is;

t is the time length for the laser sensor to rotate for a half cycle;

p1 is the space volume of the sprayer nozzle from the surface of the fruit tree canopy;

q is the required spray amount;

q is the amount of drug to be applied per unit volume;

V_nthe volume of the fruit tree canopy unit is detected in real time;

W_nthe air quantity correspondingly required for the detected canopy;

h is the spraying height of the spray head;

sigma 1 is the angle of the laser beam which is output by the angle sensor and hits the bottommost part of the surface of the canopy;

σ 2 is the angle at which the angle sensor outputs the laser beam that strikes the topmost portion of the canopy surface.

In the step 2, the image data processing control module 2 converts the calculation result of the porosity into a digital signal through signal processing, then carries out grading processing on the sparsity of the canopy, and sends the processing result to the laser data processing control module 5; the digital signals of the calculation results of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, the larger the K value of the void ratio is, the more sparse the canopy is, and K1 is more than K2 is more than K3;

in the step 3, three different circular motion interval times t1, t2 and t3 are respectively set corresponding to three sparse degree grades of sparse K1, medium K2 and dense K3, and t1> t2> t3 so as to adapt to volume detection at different sparse and dense degrees of the canopy.

A fruit tree profiling method based on laser detection and image processing technology and utilizing the fruit tree profiling sprayer comprises a centering profiling spraying mode and specifically comprises the following steps:

step 1: reading the position and row spacing data of the fruit tree, and collecting an image of the fruit tree;

the data processing control system reads the fruit tree position and planting row spacing L from the fruit tree planting database_{Line of}The sprayer operates along the middle position of two rows of fruit trees, and when the sprayer moves to a position corresponding to the position of the fruit trees, the image data processing control module 2 controls the left camera 1 and the right camera 3 to respectively collect images of the fruit trees on the left side and the right side;

step 2: adjusting the position of the spraying machine, collecting the fruit tree image again, and calculating the porosity of the fruit tree canopy;

carrying out image and morphological processing on the acquired fruit tree image to obtain a binary image only containing a fruit tree canopy, marking the binary image, framing out a maximum communication area of the canopy, calculating the center line of a minimum external rectangle of the communication area, positioning the center line of the fruit tree canopy, moving the spraying machine to enable a camera of the image acquisition device to correspond to the center line of the fruit tree canopy, and acquiring the fruit tree image again;

carrying out image segmentation and morphological processing on the fruit tree image collected again to obtain a binary image only containing a fruit tree canopy, carrying out region filling on the binary image of the fruit tree image collected again, then calculating the void ratio K of the fruit tree canopy through the following formula, and taking the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂The total pixel number of the pixel value of 1 in the binary image after the area filling;

and step 3: performing variable scanning to obtain the volume of the canopy of the fruit tree;

the laser data processing control module 5 respectively controls the first rotating motor 607 and the second rotating motor 611 to be started at a certain rotating speed, and the laser data processing control module 5 respectively sets the left laser sensor 614 and the right laser sensor 605 at different scanning angular speeds S according to the fruit tree canopy porosity K at the left and right sides_{Laser wheel}Detecting fruit trees on the left side and the right side; the laser data processing control module 5 calculates the volume of the fruit tree canopies on the left side and the right side according to the data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610 by the following formula:

y＝f(x)；

ph＝(L_i+R)×sinσ；

in the formula (I), the compound is shown in the specification,

x is the position information of the laser boundary point obtained by each scanning;

y is the fitted contour curve of the canopy after each scan;

L_ithe length of the laser beam that reaches the crown surface;

ph is a vertical projection taking the position of the angle sensor as a starting point and taking the surface of the crown hit by the laser beam as an end point;

r is the radius of the laser wheel;

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

H_maxvertical projection at the highest laser point;

H_minis the lowest laser point time sagPerforming direct projection;

v is the volume of the fruit tree canopy;

and 4, step 4: making a decision on spraying;

the laser data processing control module respectively compares the left and right detected volumes of the fruit tree canopies with a preset standard spraying decision value, when the volumes of the fruit tree canopies are smaller than the standard spraying decision value, the spraying operation is not selected, and the spraying machine is started to be arranged in front until the next fruit tree position; when the volume of the fruit tree canopy is larger than or equal to the standard spraying decision value, selecting to carry out spraying operation, and continuing the next step;

and 5: acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of a spray head;

the spray control module 27 responds to the tool operating speed S from the speed sensor 29_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time, the spray control module 27 controls the medicine application device to start working; the spraying control module 27 calculates the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H＝(L_i1+L_in+2R)×sinσ；

L₀＝(L_i+R)cosσ；

L_i'＝L_{line of}/2；

L＝L_i′-L₀；

W＝P2+V；

Q＝V*q；

Swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is the real-time rotating angle of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

h is the height of the crown;

L_{line of}Is the planting row spacing;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀a horizontal projection connecting the center of the laser wheel and the length of the laser beam reaching the surface of the canopy;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

p2 is the space volume of the sprayer before the distance from the fruit tree;

v is the volume of the fruit tree canopy;

w is the required air volume;

q is the required spray amount;

q is the amount of drug to be administered per unit volume.

In the step 2, the image data processing control module 2 converts the calculation result of the porosity into a digital signal through signal processing, then carries out grading processing on the sparsity of the canopy, and sends the processing result to the laser data processing control module 5; the digital signals of the calculation results of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, the larger the K value of the void ratio is, the more sparse the canopy is, and K1 is more than K2 is more than K3;

in the step 3, three different laser sensor scanning angular velocities s1, s2 and s3 are respectively set corresponding to three crown layer sparsity levels of sparsity K1, medium K2 and dense K3, and s1< s2< s3 so as to adapt to volume detection at different crown layer sparsity degrees.

Compared with the prior art, the invention has the beneficial effects that:

1) the invention considers the phenomena of bad fruit trees such as diseases, death and the like in the orchard, adopts a real-time profiling spraying mode for the orchard with less diseases, death and bad fruit trees, and adopts a centering profiling spraying mode for pre-judging whether to spray or not for the orchard with disease death and higher replanting rate of the fruit trees, thereby improving the applicability of the profiling spraying machine;

2) the invention greatly reduces the cost of the laser sensor in the profiling spraying application, only two laser sensor devices are used for simultaneously profiling the fruit trees on two sides of the spraying machine, and the profiling surface basically covers the fruit tree areas facing the left side and the right side of the spraying machine;

3) the method for scanning the semi-circular motion by using the laser sensor solves the problems that the shape of the causal tree is limited and the installation position of the laser sensor needs to be adjusted, and improves the profiling efficiency;

4) the method for semi-circle scanning by the laser sensor is adopted to fit the volume of the canopy, the spraying angle and the spraying height are obtained, and the precision of orchard profiling spraying is improved by adjusting the spraying parameters in real time;

5) according to the method, the density characteristics of the canopy are considered, the image processing technology is combined, the influence of the density degree of the target canopy on spraying and laser profiling is considered, variable detection and variable pesticide application are carried out according to the density degree of the canopy, and therefore profiling spraying is more intelligent;

6) according to the invention, the height of the canopy is detected in real time, the swinging height and angle of the spray head are adjusted in real time, and the spraying accuracy is improved.

Drawings

FIG. 1 is a schematic structural diagram of a fruit tree profiling sprayer based on laser detection and image processing technology;

FIG. 2 is a schematic structural diagram of the laser detection device 6;

FIG. 3a is a segmented canopy binary image;

FIG. 3b is a fully-enclosed image of the canopy region of the fruit tree after the region of FIG. 3a is filled;

FIG. 4 is a schematic view of processing a center image of a canopy in a centered anti-aliasing spray;

FIG. 5a is a schematic diagram of a real-time profiling spray canopy volume calculation method;

FIG. 5b is a schematic diagram of a method for calculating the volume of a centered contoured spray canopy;

FIG. 6a is a schematic diagram of a real-time profiled spray process;

FIG. 6b is a schematic view of a centered contoured spray process;

FIG. 7a is a schematic diagram of the calculation of the equivalent volume of the air volume during real-time profiling;

FIG. 7b is a schematic diagram of the calculation of the equivalent volume of the air volume during the centering profiling;

FIG. 8 is a schematic illustration of a profile spray calculation relationship;

FIG. 9 is a flow chart of a real-time profiling spraying method;

fig. 10 is a flow chart of a method of centering a contoured spray.

Wherein the reference numerals are:

1 left camera 2 image processing control module

3 right camera 4 camera mounting bracket

5 laser data processing control module 6 laser detection device

601 base 602 motor installation pole

603 bracket 604 first limit piece

605 right laser sensor 606 laser wheel

607 first rotating electric machine 608 second spacing piece

609 second link 610 second angle sensor

611 first angle sensor of second rotating electric machine 612

613 first link 614 left laser sensor

7 laser detection mounting rack 8 right moving slide block

9 right bracket and 10 right screw rod

11 right rotating electrical machine 12 right nozzle

13 right fluid pipeline 14 right driving motor

15 left bracket 16 left fluid pipeline

17 flow pump 18 fan

19 right regulating blade 20 left regulating blade

21 left driving motor and 22 left screw rod

23 left moving slide block 24 left rotating motor

25 left spray head 26 walking motor

27 spray control module 28 vehicle body chassis

29 speed sensor 30 medicine chest

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

As shown in fig. 1, the fruit tree profiling sprayer based on the laser detection and image processing technology comprises a vehicle body chassis 28, a pesticide applying device, an image acquisition device, a laser detection device 6 and a data processing control system.

The vehicle body chassis 28 is of a wheel type structure and is driven to move forward by a walking motor 26 arranged on the vehicle body chassis 28; the vehicle body chassis 28 is provided with a speed sensor 29 for acquiring the operating speed of the implement.

The pesticide applying device comprises a pesticide box 30, a flow pump 17, a fan 18, a spray head up-and-down moving and swinging device, a left spray head 25 and a right spray head 12. The medicine box 30 is installed on the vehicle body chassis 28, a liquid outlet of the medicine box 30 is sequentially connected with the flow pump 17 and the fan 18 through pipelines, and a left air outlet pipe and a right air outlet pipe of the fan 18 are respectively connected with the left spray head 25 and the right spray head 12 through the left fluid pipeline 16 and the right fluid pipeline 13.

Preferably, a left adjusting sheet 20 and a right adjusting sheet 19 for adjusting the air volume are respectively arranged inside the left air outlet pipe and the right air outlet pipe of the fan 18.

The left spray head 25 and the right spray head 12 are respectively installed on the left side and the right side of the rear part of the vehicle body chassis 28 through the spray head up-down moving swing device, and the spray head up-down moving swing device can adjust the height and the spray angle of the spray head according to the information of the fruit tree canopy, so that fruit tree profiling spraying is realized.

The up-and-down movement swinging device of the spray head comprises a left driving motor 21, a right driving motor 14, a left lead screw 22, a right lead screw 10, a left bracket 15, a right bracket 9, a left moving slide block 23, a right moving slide block 8, a left rotating motor 24 and a right rotating motor 11.

The left screw 22 and the left bracket 15 which are mutually parallel are vertically arranged at the left side of the rear part of the vehicle body chassis 28, and the right screw 10 and the right bracket 9 which are mutually parallel are vertically fixedly connected at the right side of the rear part of the vehicle body chassis 28; the left moving sliding block 23 is sleeved on the left screw rod 22 and the left support 15, and the right moving sliding block 8 is sleeved on the right screw rod 10 and the right support 9; the left driving motor 21 and the right driving motor 14 respectively drive the left lead screw 22 and the right lead screw 10 to rotate, so that the left moving slide block 23 and the right moving slide block 8 perform vertical linear motion.

The left rotating motor 24 and the right rotating motor 11 are respectively and fixedly connected to the left moving slide block 23 and the right moving slide block 8; wherein, the rotating shaft of the left rotating motor 24 is connected with the left nozzle 25, and the rotating shaft of the right rotating motor 11 is connected with the right nozzle 12.

The left spray nozzle 25 and the right spray nozzle 12 adopt gas-liquid double-flow spray nozzles, and the spray nozzle bodies are provided with atomizing chambers.

The image acquisition device comprises a camera mounting frame 4, a left camera 1 and a right camera 3, wherein the camera mounting frame 4 is vertically and fixedly connected to the front part of the vehicle body chassis 28, and the left camera 1 and the right camera 3 are respectively mounted on the left side and the right side of the camera mounting frame 4.

The left camera 1 and the right camera 3 are ordinary CCD cameras.

The laser detection device 6 comprises a laser detection mounting frame 7, a base 601, a motor mounting rod 602, a bracket 603, a laser wheel 606, a left laser sensor 614, a right laser sensor 605, a first rotating motor 607, a second rotating motor 611, a first connecting rod 613 and a second connecting rod 609.

The laser detection mounting rack 7 is vertically and fixedly connected to the middle of the vehicle body chassis 28, and the base 601 is fixedly connected to the rear end face of the laser detection mounting rack 7.

As shown in fig. 2, the front ends of a pair of horizontal brackets 603 are respectively and vertically fixed on the upper and lower parts of the base 601, and the upper and lower ends of the laser wheel 606 parallel to the vertical plane are respectively and fixedly connected with the rear ends of the two brackets 603. The motor mounting rod 602 is fixedly connected between the rear ends of the two brackets 603. The left laser sensor 614 and the right laser sensor 605 are slidably mounted on the left half circumference and the right half circumference of the laser wheel 606 respectively to scan the fruit tree canopies on the left side and the right side respectively.

The first rotating motor 607 and the second rotating motor 611 are concentrically and fixedly connected to the motor mounting rod 602 and the base 601, respectively, with the laser wheel 606. The power output shaft of the first rotating electric machine 607 is connected to the left laser sensor 614 through a first link 613, and the power output shaft of the second rotating electric machine 611 is connected to the right laser sensor 605 through a second link 609.

A first angle sensor 612 is provided between the first rotating electric machine 607 and the first link 613, and a second angle sensor 610 is provided between the second rotating electric machine 611 and the second link 609.

The rear ends of the two brackets 603 are respectively provided with a first limiting piece 604 and a second limiting piece 608.

The first rotating motor 607 drives the left laser sensor 614 to make a semi-circular motion along the left portion of the laser wheel 606 through the first connecting rod 613, and the second rotating motor 611 drives the right laser sensor 605 to make a semi-circular motion along the right portion of the laser wheel 606 through the second connecting rod 609. The first and second position-limiting pieces 604 and 608 limit the displacement of the right and left laser sensors 605 and 614. The first angle sensor 612 and the second angle sensor 610 are used for detecting real-time movement angles of the left laser sensor 614 and the right laser sensor 605, respectively.

The distance between the laser detection device 6 and the ground is 30-80 cm.

The data processing control system comprises an image data processing control module 2, a laser data processing control module 5 and a spray control module 27.

Image data processing control module 2 installs on camera mounting bracket 4 to be connected with left camera 1, right camera 3, laser data processing control module 5 and spraying control module 27, receive, handle the fruit tree canopy picture that left camera 1 and right camera 3 gathered, and send the processing result for laser data processing control module 5 and spraying control module 27.

The laser data processing control module 5 is installed on the laser detection mounting frame 7, and is connected with the speed sensor 29, the first rotating motor 607, the second rotating motor 611, the left laser sensor 614, the right laser sensor 605, the first angle sensor 612, the second angle sensor 610 and the spray control module 27. The laser data processing control module 5 controls the start, stop and movement speed of the first rotating motor 607 and the second rotating motor 611 according to the tool operation speed returned by the speed sensor 29, the spacing distance between the camera mounting frame 4 and the laser detection mounting frame 7 and the processing result sent by the image data processing control module 2; and the data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610 are received and processed, and the processing result is sent to the spray control module 27.

The spraying control module 27 is arranged on a vehicle body chassis 28 and is connected with a speed sensor 29, a flow pump 17 of the pesticide applying device, a fan 18, a left driving motor 21, a right driving motor 14, a left rotating motor 24 and a right rotating motor 11, and is used for calculating spraying requirements and spraying delay time according to processing results sent by the laser data processing control module 5 and machine tool operation speeds returned by the speed sensor 29, further adjusting the pesticide applying device according to the spraying requirements and starting spraying.

Preferably, the distance between the camera of the image acquisition device and the laser sensor of the laser detection device 6 is 0.5m to 1.5 m.

Preferably, the spacing distance between the laser sensor of the laser detection device 6 and the spray head of the application device is 0.5-1.5 m.

The invention provides a fruit tree profiling method based on laser detection and image processing technologies, wherein different profiling spraying modes are selected according to the death rate and the disease rate of fruit trees in an orchard. When the death rate and the disease rate of fruit trees in the orchard are low, a real-time profiling spraying mode is selected; when the death rate and the disease rate of fruit trees in the orchard are higher, a centering profiling spraying mode is selected.

The real-time profiling spraying mode obtains the real-time canopy volume of laser detection in the advancing process of the spraying machine, and real-time profiling variable spraying is carried out.

Firstly, reading the position and row spacing data of a fruit tree, acquiring an image of the fruit tree through an image acquisition device, calculating the void ratio of a crown layer of the fruit tree, and representing the sparsity of the crown layer of the fruit tree by the void ratio; secondly, changing the movement interval time of the laser sensor according to different sparsity degrees of the canopy of the fruit tree, and realizing variable detection; thirdly, calculating the volume of the canopy of the fruit tree according to the laser scanning result; and finally, acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volume of the fruit tree canopy, and spraying.

As shown in fig. 9, the real-time profiling spray pattern comprises the following specific steps:

step 1: and reading the position and row spacing data of the fruit tree, and collecting the image of the fruit tree.

The data processing control system reads the fruit tree position and planting row spacing L from the fruit tree planting database_{Line of}And when the sprayer moves to a position corresponding to the fruit tree position, the image data processing control module 2 controls the left camera 1 and the right camera 3 to respectively collect fruit tree images on the left side and the right side.

Step 2: and calculating the porosity of the fruit tree canopy.

Using MATALB 2018a to perform image segmentation and morphological processing on the acquired fruit tree image to obtain a binary image only containing a fruit tree canopy, performing region filling on the binary image, then calculating the void ratio K of the fruit tree canopy through the following formula, and using the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂Is a regionThe pixel value in the binary image after the domain filling is 1;

the step 2 specifically comprises the following steps:

1) the Retinex image equalization algorithm is used for carrying out image segmentation preprocessing on the collected fruit tree images, the Retinex algorithm enables R, G and B component gray levels of the original image to be compressed, the dynamic range of the compressed gray levels is compressed from 0-255 to 50-250, and the dynamic range of the overexposed area is compressed from 100-255 to 200-255, so that the image with uniform contrast is obtained, the definition of the main body outline of the image is improved, and the detail quality of the image is increased.

2) Taking a fruit tree image three-channel R, G, B with balanced illumination model as an input feature, selecting a fuzzy parameter of 2 and a clustering number of 2, and carrying out image segmentation and morphological processing on a fruit tree canopy image by carrying out an FCM clustering algorithm on a clustering center with a maximum 2G-R-B value to obtain a binary image only containing a canopy, wherein the binary image is taken as a canopy segmentation result image as shown in FIG. 3a, a background pixel value in the canopy segmentation result image is 0, and a canopy region pixel value is 1;

3) the total pixel number with the pixel value of 1 in the statistical canopy segmentation result graph is recorded as R₁And the area is a fruit tree canopy area with gaps. And (3) performing area filling on the canopy segmentation result graph to obtain a complete tree canopy area without gaps, defining the complete tree canopy area as a totally-enclosed fruit tree canopy area with the gap number of 0 as shown in fig. 3b, and counting the total pixel number with the pixel value of 1 in the binary image and recording the total pixel number as R₂. Then calculating the porosity K of the fruit tree canopy by the following formula:

4) the image data processing control module 2 converts the void ratio calculation result into a digital signal through signal processing, then carries out the grading processing of the canopy sparsity, and sends the processing result to the laser data processing control module 5. In the embodiment, the digital signals of the calculation result of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, and the bigger the value of the void ratio K is, the more sparse the canopy is, so that the values of K1> K2> K3 are determined according to the growth period of the fruit tree.

And step 3: and (4) variable scanning, and acquiring the volume of the fruit tree canopy unit in real time.

The laser data processing control module 5 processes the machine tool working speed S returned by the speed sensor 29_{Spraying machine}And the spacing distance between the camera and the laser sensor, and calculating the delay time detected by the laser sensor; after the delay time, the laser data processing control module 5 respectively controls the first rotating motor 607 and the second rotating motor 611 to start at a certain rotating speed, and the laser data processing control module 5 respectively sets the left laser sensor 614 and the right laser sensor 605 to scan the angular velocity S according to the fruit tree canopy void ratio K at the left and right sides_{Laser wheel}And detecting the fruit trees on the left side and the right side at different movement intervals. The movement interval time is the interval time between the completion of one semi-circular movement of the left laser sensor 614 or the right laser sensor 605 on the laser wheel 606 and the start of the next semi-circular movement. The angular velocity S_{Laser wheel}Between 18 DEG/s and 42 DEG/s. The laser data processing control module 5 calculates the volumes of the fruit tree canopy units on the left side and the right side according to the data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610 by the following formula (part of calculation parameters are shown in fig. 8):

L_i'＝L_{line of}/2；

L₀＝(L_i+R)cosσ；

L＝L_i′-L₀；

H_n＝(L_i1+L_in+2R)×sinσ；

V_n＝H_n×2L×S_{Spraying machine}×T；

In the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel 606;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀for connecting laser wheelsHorizontal projection of the center with the length of the laser beam reaching the canopy surface;

L_{line of}Is the planting row spacing;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

S_{spraying machine}The operating speed of the machine tool;

t is the time length for the laser sensor to rotate for a half cycle;

V_nthe volume of the fruit tree canopy unit is detected in real time.

In this embodiment, three different circumferential motion interval times t1, t2 and t3 are respectively set corresponding to three sparsity levels of the more sparse K1, the medium K2 and the more dense K3, so as to adapt to volume detection at different density levels of the canopy. Under a certain movement speed of the sprayer and the width of the fruit tree, the longer the scanning interval is, the fewer the times of detection by the laser sensor are, and in the real-time profiling spraying mode, the fruit tree with dense canopy needs more application amount, so that the settings of t1, t2 and t3 are set. For fruit trees with different canopy sparsity levels on two sides in the advancing process of the spraying machine, the laser sensors respectively perform semi-circular motion at different time intervals, and variable detection is achieved.

The method comprises the steps of calculating the volume of a canopy according to laser information returned by a laser sensor to achieve the purpose of profiling spraying, under the condition that two motions of advancing a spraying machine and scanning the semi-circle of the laser sensor are simultaneously carried out, the curve shape of laser points hitting the surface of the canopy is 1/4 period of sine distribution, and setting the scanning angular speed S of the laser sensor to reduce errors_{Laser wheel}Working speed S of the machine_{Spraying machine}The relationship between them is: s_{Laser wheel}>>S_{Spraying machine}Sinusoidal shape of 1/4 cycle at this timeClose to the vertical line, as shown in fig. 5 a.

The calculated volume of the canopy when the laser sensor scans a half circle is recorded as a unit, as shown in fig. 5 a. Equating the canopy unit calculated when the laser sensor moves for half a cycle to be a cuboid, wherein the length of the cuboid is 2L as shown in the figure, and L is the distance from the surface of the canopy to the center of the trunk; the height of the cuboid is the height H of the crown; the width is the distance that the sprayer walks within the time T that the laser sensor completes one half-cycle motion, S_{Spraying machine}And x T. And (4) solving the volume of the canopy after each scanning along with the travel of the spraying machine.

Fig. 6a is a schematic diagram of a real-time profiling spraying method under different canopy densities. The figure reflects that as the density of the canopy increases, the laser sensor movement interval becomes shorter. The higher the density of the canopy is, the larger the needed pesticide application area is, so the total spraying amount of the fruit trees with the canopy porosity of K3 is larger than that of the canopy when the canopy porosity of K1 is larger. And laser detection is carried out according to different canopy densities, and spraying is carried out, so that the variable spraying detection process is realized.

And 4, step 4: acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of a spray head;

the spray control module 27 responds to the tool operating speed S from the speed sensor 29_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time has elapsed, the spray control module 27 controls the applicator to begin operation. The spraying control module 27 calculates the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H_n＝(L_i1+L_in+2R)×sinσ；

W_n＝P1+V_n；

Q＝V_n*q；

swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

r is the radius of the laser wheel;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

s_{spraying machine}The advancing speed of the sprayer is;

t is the time length for the laser sensor to rotate for a half cycle;

p1 is the space volume of the sprayer nozzle from the surface of the fruit tree canopy;

q is the required spray amount;

q is the application dosage required by unit volume, and the specific value is determined according to the spraying object;

V_nthe volume of the fruit tree canopy unit is detected in real time;

W_nthe air quantity correspondingly required for the detected canopy;

h is the spraying height of the spray head;

sigma 1 is the angle of the laser beam which is output by the angle sensor and hits the bottommost part of the surface of the canopy;

σ 2 is the angle at which the angle sensor outputs the laser beam that strikes the topmost portion of the canopy surface.

The required air volume is different under different canopy volumes, on the premise of a replacement principle, the calculated air volume required by the fruit tree is equivalent to the sum of the canopy volume of the fruit tree and the space volume P1 from the front of the fan to the fruit tree, wherein the canopy volume of the fruit tree is obtained by calculation in the step 3, the space volume of the sprayer nozzle from the surface of the canopy of the fruit tree is equivalent to the volume of a rectangular pyramid,the equivalent relationship is shown in FIG. 7a, the height L of the rectangular pyramid_i' is the distance from the center of the laser wheel to the surface of the canopy of the fruit tree, the bottom surface of the rectangular pyramid is equivalent to a rectangle, and the length H of the rectangle_nThe height of the canopy unit is detected in real time, and the width is the distance that the laser sensor sprays within the time T of completing one-time semi-circle movement, S_{Spraying machine}×T。

And calculating the moving distance of the spraying machine according to the installation distance of the laser detection device and the speed of the spraying machine returned by the speed sensor 29 of the spraying machine so as to adjust the spraying machine to move to the front of the spray head to be positioned at the center of the canopy of the fruit tree. Calculating the advancing time of the sprayer, and controlling the sliding block to adjust the height of the bracket through the tree crown height information H so that the sprayer sprays at the height H. Meanwhile, the angle sensor outputs an angle sigma 1 of a laser beam hitting the bottommost part of the surface of the canopy and an angle sigma 2 of a laser beam hitting the topmost part, and the spray head is controlled to swing between angles [ sigma 1, sigma 2 ].

In the centering profiling spraying mode, firstly, reading the position and row spacing data of a fruit tree, acquiring an image of the fruit tree through an image acquisition device, positioning the central line of a canopy of the fruit tree, moving a spraying machine to enable a camera of the image acquisition device to correspond to the central line of the canopy of the fruit tree, acquiring the image of the fruit tree again, calculating the void ratio of the canopy of the fruit tree, and representing the sparse degree of the canopy of the fruit tree through the void ratio; secondly, changing the scanning speed of a laser sensor according to different sparsity degrees of the canopy of the fruit tree, and performing variable detection; thirdly, fitting the canopy contour by using the captured laser points according to the laser scanning result, and calculating the volume of the fruit tree canopy; then, whether spray operation is carried out or not is decided according to the volume of the fruit tree canopy; if the fruit tree canopy is judged to be spraying, the air quantity and the spraying quantity required by spraying, the spraying height and the swing angle range of the spray head are obtained according to the volume of the fruit tree canopy, and spraying is carried out. If the fruit tree is judged not to be sprayed, the spraying machine continues to move to the position of the fruit tree at the next moment.

As shown in fig. 10, the centering profiling spray pattern specifically includes the steps of:

step 1: and reading the position and row spacing data of the fruit tree, and collecting the image of the fruit tree.

The data processing control system reads the fruit from the fruit tree planting databaseTree position and planting row spacing L_{Line of}And when the sprayer moves to a position corresponding to the fruit tree position, the image data processing control module 2 controls the left camera 1 and the right camera 3 to respectively collect left and right fruit tree images.

Step 2: adjusting the position of the spraying machine, collecting the fruit tree image again, and calculating the porosity of the fruit tree canopy.

Carrying out image and morphological processing on the acquired fruit tree image by using MATALB 2018a to obtain a binary image only containing a fruit tree canopy, marking the binary image, framing out a maximum connected region of the canopy, calculating the center line of a minimum external rectangle of the connected region, positioning the center line of the fruit tree canopy, moving the sprayer to enable a camera of the image acquisition device to correspond to the center line of the fruit tree canopy, and acquiring the fruit tree image again;

carrying out image segmentation and morphological processing on the fruit tree image collected again by using MATALB 2018a to obtain a binary image only containing a fruit tree canopy, carrying out region filling on the binary image of the fruit tree image collected again, then calculating the void ratio K of the fruit tree canopy by using the following formula, and taking the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂The total pixel number of the pixel value of 1 in the binary image after the area filling;

the step 2 specifically comprises the following steps:

1) the Retinex image equalization algorithm is used for carrying out image segmentation preprocessing on the collected fruit tree images, the Retinex algorithm enables R, G and B component gray levels of the original image to be compressed, the dynamic range of the compressed gray levels is compressed from 0-255 to 50-250, and the dynamic range of the overexposed area is compressed from 100-255 to 200-255, so that the image with uniform contrast is obtained, the definition of the main body outline of the image is improved, and the detail quality of the image is increased.

2) Taking a fruit tree image three-channel R, G, B with balanced illumination model as an input feature, selecting a fuzzy parameter of 2 and a clustering number of 2, and carrying out image segmentation and morphological processing on a fruit tree canopy image by carrying out an FCM clustering algorithm on a clustering center with a maximum 2G-R-B value to obtain a binary image only containing a canopy, wherein the binary image is taken as a canopy segmentation result image as shown in FIG. 3a, a background pixel value in the canopy segmentation result image is 0, and a canopy region pixel value is 1;

3) and marking the canopy segmentation result graph by adopting a bwconncomp function, selecting a maximum canopy communication area of the marked image by utilizing a bounding box attribute character string frame in a regionprops function, and calculating the central line of a minimum external rectangle of the communication area, wherein the central line is recorded as the central line of the fruit tree canopy. As shown in FIG. 4, the box is represented as a circumscribed rectangle containing the maximum connected area of the entire canopy, SL₁Represents the centerline, SL, of the canopy of the fruit tree₂Representing the centerline of the entire image. SL because the centerline of the canopy of the fruit tree may be deviated from the trunk of the fruit tree (the position of the fruit tree read by the sprayer)₁And SL₂The positions of the sprayers need to be adjusted because the sprayers are not overlapped. Calculating SL₁Abscissa pixel position R₃And SL₂Abscissa pixel position R₄Reading the fruit tree position Q1 at the moment, and calculating the actual position Q2 of the position of the fruit tree canopy center as follows:

the image processing control platform returns Q2 to the spraying control module 27, the spraying control module 27 outputs signals, and the position of the spraying machine is adjusted, so that the camera of the image acquisition device corresponds to the center line of the canopy of the fruit tree.

4) Obtaining the fruit tree image again through the image acquisition device, repeating the step 1) and the step 2), and counting the total pixel number with the pixel value of 1 in the canopy segmentation result image as R₁And the area is a fruit tree canopy area with gaps. Filling the area of the canopy segmentation result graph to obtain a complete crown area without gaps, and defining the area as a totally-enclosed tree crown area with the number of the gaps being 0 as shown in FIG. 3bThe total pixel number of the binary image with the pixel value of 1 is counted and recorded as R₂. Then calculating the porosity K of the fruit tree canopy by the following formula:

5) the image data processing control module 2 converts the void ratio calculation result into a digital signal through signal processing, then carries out the grading processing of the canopy sparsity, and sends the processing result to the laser data processing control module 5. In the embodiment, the digital signals of the calculation result of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, and the bigger the value of the void ratio K is, the more sparse the canopy is, so that the values of K1> K2> K3 are determined according to the growth period of the fruit tree.

And step 3: and (5) variable scanning to obtain the volume of the canopy of the fruit tree.

The laser data processing control module 5 respectively controls the first rotating motor 607 and the second rotating motor 611 to be started at a certain rotating speed, and the laser data processing control module 5 respectively sets the left laser sensor 614 and the right laser sensor 605 at different scanning angular speeds S according to the fruit tree canopy porosity K at the left and right sides_{Laser wheel}And detecting the fruit trees on the left side and the right side. The laser data processing control module 5 calculates the volume of the fruit tree canopies on the left side and the right side according to the data collected by the left laser sensor 614, the right laser sensor 605, the first angle sensor 612 and the second angle sensor 610 by the following formula:

y＝f(x)；

ph＝(L_i+R)×sinσ；

in the formula (I), the compound is shown in the specification,

x is the position information of the laser boundary point obtained by each scanning;

y is the fitted canopy profile curve after each scan, as shown in FIG. 5 b;

L_ithe length of the laser beam that reaches the crown surface;

ph is a vertical projection taking the position of the angle sensor as a starting point and taking the surface of the crown hit by the laser beam as an end point;

r is the radius of the laser wheel;

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

H_maxvertical projection at the highest laser point;

H_minvertical projection at the lowest laser point;

v is the volume of the fruit tree canopy.

Three different laser sensor scanning angular velocities s1, s2 and s3 are respectively arranged corresponding to three canopy sparsity levels of sparsity K1, medium K2 and dense K3, and s1 is smaller than s2 and smaller than s3, so that the method is suitable for volume detection under different canopy density degrees. FIG. 6b is a schematic diagram of a centered, contoured spray process with varying porosity. The larger the void ratio is, the slower the laser sensor moves to reduce the problem of laser loss when the canopy is sparse, so the output signal with the larger laser signal loss ratio is set as follows: the fruit trees with crown void ratio signals of K1, K2 and K3 at two sides move at speeds of s1, s2 and s3 corresponding to the laser sensor respectively in the process of the sprayer moving, wherein s1 is less than s2 is less than s 3.

And calculating a canopy profile curve. The laser data processing control module receives information of crown boundary points acquired by the laser sensor, performs curve fitting by using an interpolation algorithm, programs the algorithm through a QT compiler, solidifies the program into the singlechip through a serial port, and can directly obtain a crown contour fitting curve through data measured by the laser sensor.

And 4, step 4: decision-making spray

The laser data processing control module respectively compares the left and right detected volumes of the fruit tree canopies with a preset standard spraying decision value, when the volumes of the fruit tree canopies are smaller than the standard spraying decision value, the spraying operation is not selected, and the spraying machine is started to be arranged in front until the next fruit tree position; when the volume of the fruit tree canopy is larger than or equal to the standard spraying decision value, selecting to carry out spraying operation, and continuing the next step;

the method for selecting the standard spray decision value in the embodiment comprises the following steps: presetting the volume v of the first five fruit trees which are normal fruit trees in the spraying process of a spraying machine and storing the five fruit trees₁,v₂,v₃,v₄,v₅Calculating the standard deviation of the five fruit trees

The volume value of the normal fruit tree is stored as the volume value of the normal fruit tree, and is compared with the volume of the canopy to be sprayed by the spraying machine, when V is more than or equal to V_sAt this time, the spray is started.

And 5: and acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of the spray head.

The spray control module 27 responds to the tool operating speed S from the speed sensor 29_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time has elapsed, the spray control module 27 controls the applicator to begin operation. The spraying control module 27 calculates the air volume (as shown in fig. 7 b) required by spraying, the spraying volume, the spraying height and the swing angle range of the spray head (part of calculation parameters are shown in fig. 8) according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H＝(L_i1+L_in+2R)×sinσ；

L₀＝(L_i+R)cosσ；

L_i'＝L_{line of}/2；

L＝L_i′-L₀；

W＝P2+V；

Q＝V*q；

Swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is the real-time rotating angle of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

h is the height of the crown;

L_{line of}Is the planting row spacing;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀a horizontal projection connecting the center of the laser wheel and the length of the laser beam reaching the surface of the canopy;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

p2 is the space volume of the sprayer before the distance from the fruit tree;

v is the volume of the fruit tree canopy;

w is the required air volume;

q is the required spray amount;

q is the needed application amount of the unit volume, and the specific value is determined according to the spraying object.

And controlling the sliding block to adjust the height of the support through the tree crown height information H, so that the spray head sprays under the height H, outputting an angle sigma 1 of a laser beam hitting the bottommost part of the surface of the canopy and an angle sigma 2 of a laser beam hitting the topmost part by the angle sensor, and controlling the spray head to swing between angles [ sigma 1, sigma 2 ].

Claims (10)

1. The utility model provides a fruit tree profiling sprayer based on laser detection and image processing technique, includes automobile body chassis (28) and the device of giving medicine to the poor free of charge, the device of giving medicine to the poor free of charge includes medical kit (30), flow pump (17), fan (18), left shower nozzle (25) and right shower nozzle (12), and the liquid outlet of medical kit (30) connects gradually flow pump (17) and fan (18) through the pipeline, and two play tuber pipes are connected with left shower nozzle (25) and right shower nozzle (12) through left fluid pipeline (16) and right fluid pipeline (13) respectively about fan (18), its characterized in that:

a speed sensor (29) for acquiring the operation speed of the machine tool is arranged on the vehicle body chassis (28);

the pesticide applying device further comprises a spray head up-and-down moving swing device; the left spray head (25) and the right spray head (12) are respectively arranged at the left side and the right side of the rear part of the vehicle body chassis (28) through a spray head up-down moving swinging device;

the fruit tree profiling sprayer further comprises an image acquisition device, a laser detection device (6) and a data processing control system;

the image acquisition device comprises a camera mounting rack (4), a left camera (1) and a right camera (3), wherein the camera mounting rack (4) is vertically and fixedly connected to the front part of a vehicle body chassis (28), and the left camera (1) and the right camera (3) are respectively mounted on the left side and the right side of the camera mounting rack (4);

the laser detection device (6) comprises a laser detection mounting frame (7), a base (601), a motor mounting rod (602), a support (603), a laser wheel (606), a left laser sensor (614), a right laser sensor (605), a first rotating motor (607), a second rotating motor (611), a first connecting rod (613) and a second connecting rod (609);

the laser detection mounting rack (7) is vertically and fixedly connected to the middle of the vehicle body chassis (28), and the base (601) is fixedly connected to the rear end face of the laser detection mounting rack (7);

the front ends of a pair of horizontal brackets (603) are respectively and vertically fixedly connected to the upper part and the lower part of the base (601), and the upper end and the lower end of a laser wheel (606) parallel to a vertical plane are respectively and fixedly connected with the rear ends of the two brackets (603); the motor mounting rod (602) is fixedly connected between the rear ends of the two brackets (603); the left laser sensor (614) and the right laser sensor (605) are respectively slidably arranged on the left half circumference and the right half circumference of the laser wheel (606) and respectively scan the fruit tree canopies on the left side and the right side;

the first rotating motor (607) and the second rotating motor (611) are concentrically and fixedly connected with the laser wheel (606) on the motor mounting rod (602) and the base (601) respectively; the power output shaft of the first rotating motor (607) is connected with the left laser sensor (614) through a first connecting rod (613), and the power output shaft of the second rotating motor (611) is connected with the right laser sensor (605) through a second connecting rod (609);

a first angle sensor (612) is arranged between the first rotating motor (607) and the first connecting rod (613), and a second angle sensor (610) is arranged between the second rotating motor (611) and the second connecting rod (609);

the data processing control system comprises an image data processing control module (2), a laser data processing control module (5) and a spraying control module (27);

the image data processing control module (2) is installed on the camera installation frame (4), is connected with the left camera (1), the right camera (3), the laser data processing control module (5) and the spraying control module (27), receives and processes fruit tree canopy pictures acquired by the left camera (1) and the right camera (3), and sends processing results to the laser data processing control module (5) and the spraying control module (27);

the laser data processing control module (5) is installed on the laser detection installation frame (7) and is connected with the speed sensor (29), the first rotating motor (607), the second rotating motor (611), the left laser sensor (614), the right laser sensor (605), the first angle sensor (612), the second angle sensor (610) and the spray control module (27); the laser data processing control module (5) controls the starting, stopping and moving speeds of the first rotating motor (607) and the second rotating motor (611) according to the machine tool operation speed returned by the speed sensor (29), the spacing distance between the camera mounting frame (4) and the laser detection mounting frame (7) and the processing result sent by the image data processing control module (2); receiving and processing data collected by a left laser sensor (614), a right laser sensor (605), a first angle sensor (612) and a second angle sensor (610), and sending processing results to a spray control module (27);

the spraying control module (27) is arranged on a chassis (28) of the vehicle body and is connected with the speed sensor (29), a flow pump (17) of the pesticide applying device, the fan (18), the left driving motor (21), the right driving motor (14), the left rotating motor (24) and the right rotating motor (11), and spraying requirements and spraying delay time are calculated according to processing results sent by the laser data processing control module (5) and machine tool operation speed returned by the speed sensor (29), so that the pesticide applying device is adjusted according to the spraying requirements and spraying is started.

2. The fruit tree profiling sprayer of claim 1, wherein:

the rear ends of the two supports (603) are respectively provided with a first limiting sheet (604) and a second limiting sheet (608) which limit the displacement of the right laser sensor (605) and the left laser sensor (614).

3. The fruit tree profiling sprayer of claim 1, wherein:

the distance between the laser detection device (6) and the ground is 30-80 cm;

the spacing distance between the vertical plane where the left camera (1) and the right camera (3) of the image acquisition device are located and the vertical plane where the left laser sensor (614) and the right laser sensor (605) of the laser detection device (6) are located is 0.5-1.5 m;

the spacing distance between the vertical plane where the left laser sensor (614) and the right laser sensor (605) of the laser detection device (6) are located and the vertical plane where the left spray head (25) and the right spray head (12) of the pesticide application device are located is 0.5-1.5 m.

4. The fruit tree profiling sprayer of claim 1, wherein:

and a left adjusting sheet (20) and a right adjusting sheet (19) for adjusting air volume are respectively arranged inside the left air outlet pipe and the right air outlet pipe of the fan (18).

5. The fruit tree profiling sprayer of claim 1, wherein:

the up-and-down movement swinging device of the spray head comprises a left driving motor (21), a right driving motor (14), a left lead screw (22), a right lead screw (10), a left bracket (15), a right bracket (9), a left moving slide block (23), a right moving slide block (8), a left rotating motor (24) and a right rotating motor (11);

the left screw rod (22) and the left bracket (15) which are mutually parallel are vertically installed on the left side of the rear part of the vehicle body chassis (28), and the right screw rod (10) and the right bracket (9) which are mutually parallel are vertically and fixedly connected on the right side of the rear part of the vehicle body chassis (28); the left moving sliding block (23) is sleeved on the left lead screw (22) and the left support (15), and the right moving sliding block (8) is sleeved on the right lead screw (10) and the right support (9); the left driving motor (21) and the right driving motor (14) respectively drive the left lead screw (22) and the right lead screw (10) to rotate, so that the left moving slide block (23) and the right moving slide block (8) do vertical linear motion;

the left rotating motor (24) and the right rotating motor (11) are respectively and fixedly connected to the left moving slide block (23) and the right moving slide block (8); wherein, the rotating shaft of the left rotating motor (24) is connected with the left spray head (25), and the rotating shaft of the right rotating motor (11) is connected with the right spray head (12).

6. The fruit tree profiling sprayer of claim 1, wherein:

the left spray head (25) and the right spray head (12) adopt gas-liquid double-flow spray heads, and an atomization chamber is arranged on the spray head body; the left camera (1) and the right camera (3) are CCD cameras.

7. A fruit tree profiling method based on laser detection and image processing technology by using the fruit tree profiling spraying machine of any one of claims 1-6, wherein the fruit tree profiling method comprises the following steps: the method comprises a real-time profiling spraying mode, and comprises the following specific steps:

step 1: reading the position and row spacing data of the fruit tree, and collecting an image of the fruit tree;

the data processing control system reads the fruit tree position and planting row spacing L from the fruit tree planting database_{Line of}The sprayer operates along the middle position of two rows of fruit trees, and when the sprayer moves to a position corresponding to the position of the fruit trees, the image data processing control module (2) controls the left camera (1) and the right camera (3) to respectively collect fruit tree images on the left side and the right side;

step 2: calculating the porosity of the fruit tree canopy;

carrying out image segmentation and morphological processing on the collected fruit tree image to obtain a binary image only containing a fruit tree canopy, carrying out region filling on the binary image, then calculating the void ratio K of the fruit tree canopy through the following formula, and taking the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂The total pixel number of the pixel value of 1 in the binary image after the area filling;

and step 3: variable scanning is carried out, and the unit volume of the canopy of the fruit tree is obtained in real time;

the laser data processing control module (5) transmits the working speed S of the machine tool back according to the speed sensor (29)_{Spraying machine}And the spacing distance between the camera and the laser sensor, and calculating the delay time detected by the laser sensor; after the delay time, the laser data processing control module (5) respectively controls the first rotating motor (607) and the second rotating motor (611) to be started at a certain rotating speed, and the laser data processing control module (5) respectively sets the left laser sensor (614) and the right laser sensor (605) to scan the angular speed S according to the fruit tree canopy porosity K at the left side and the right side_{Laser wheel}Detecting fruit trees on the left side and the right side at different movement intervals; the movement interval time is the interval time between the completion of one semi-circular movement and the start of the next semi-circular movement of the left laser sensor (614) or the right laser sensor (605) on the laser wheel (606); the laser data processing control module (5) calculates the volume of fruit tree canopy units on the left side and the right side according to data collected by the left laser sensor (614), the right laser sensor (605), the first angle sensor (612) and the second angle sensor (610) through the following formula:

L_i'＝L_{line of}/2；

L₀＝(L_i+R)cosσ；

L＝L_i′-L₀；

H_n＝(L_i1+L_in+2R)×sinσ；

V_n＝H_n×2L×S_{Spraying machine}×T；

In the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀a horizontal projection connecting the center of the laser wheel and the length of the laser beam reaching the surface of the canopy;

L_{line of}Is the planting row spacing;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

S_{spraying machine}The operating speed of the machine tool;

t is the time length for the laser sensor to rotate for a half cycle;

V_nthe volume of the fruit tree canopy unit is detected in real time;

and 4, step 4: acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of a spray head;

the spraying control module (27) transmits the working speed S of the machine tool according to the speed sensor (29)_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time, the spraying control module (27) controls the pesticide applying device to start working; the spraying control module (27) calculates the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H_n＝(L_i1+L_in+2R)×sinσ；

W_n＝P1+V_n；

Q＝V_n*q；

swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

H_ncanopy cell height for real-time detection;

r is the radius of the laser wheel;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

s_{spraying machine}The advancing speed of the sprayer is;

t is the time length for the laser sensor to rotate for a half cycle;

p1 is the space volume of the sprayer nozzle from the surface of the fruit tree canopy;

q is the required spray amount;

q is the amount of drug to be applied per unit volume;

V_nthe volume of the fruit tree canopy unit is detected in real time;

W_nthe air quantity correspondingly required for the detected canopy;

h is the spraying height of the spray head;

sigma 1 is the angle of the laser beam which is output by the angle sensor and hits the bottommost part of the surface of the canopy;

σ 2 is the angle at which the angle sensor outputs the laser beam that strikes the topmost portion of the canopy surface.

8. The method of claim 7, wherein:

in the step 2, the image data processing control module (2) converts the void ratio calculation result into a digital signal through signal processing, then carries out canopy sparsity grading processing, and sends the processing result to the laser data processing control module (5); the digital signals of the calculation results of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, the larger the K value of the void ratio is, the more sparse the canopy is, and K1 is more than K2 is more than K3;

in the step 3, three different circular motion interval times t1, t2 and t3 are respectively set corresponding to three sparse degree grades of sparse K1, medium K2 and dense K3, and t1> t2> t3 so as to adapt to volume detection at different sparse and dense degrees of the canopy.

9. A fruit tree profiling method based on laser detection and image processing technology by using the fruit tree profiling spraying machine of any one of claims 1-6, wherein the fruit tree profiling method comprises the following steps: the method comprises a centering profiling spraying mode, and comprises the following specific steps:

step 1: reading the position and row spacing data of the fruit tree, and collecting an image of the fruit tree;

the data processing control system reads the fruit tree position and planting row spacing L from the fruit tree planting database_{Line of}The sprayer operates along the middle position of two rows of fruit trees, and when the sprayer moves to a position corresponding to the position of the fruit trees, the image data processing control module (2) controls the left camera (1) and the right camera (3) to respectively collect images of the fruit trees on the left side and the right side;

step 2: adjusting the position of the spraying machine, collecting the fruit tree image again, and calculating the porosity of the fruit tree canopy;

carrying out image and morphological processing on the acquired fruit tree image to obtain a binary image only containing a fruit tree canopy, marking the binary image, framing out a maximum communication area of the canopy, calculating the center line of a minimum external rectangle of the communication area, positioning the center line of the fruit tree canopy, moving the spraying machine to enable a camera of the image acquisition device to correspond to the center line of the fruit tree canopy, and acquiring the fruit tree image again;

carrying out image segmentation and morphological processing on the fruit tree image collected again to obtain a binary image only containing a fruit tree canopy, carrying out region filling on the binary image of the fruit tree image collected again, then calculating the void ratio K of the fruit tree canopy through the following formula, and taking the void ratio K of the fruit tree canopy as a standard for reflecting the sparsity of the fruit tree canopy;

in the formula, K is the porosity of the fruit tree canopy; r₁The total pixel number of the binary image with the pixel value of 1 is used; r₂The total pixel number of the pixel value of 1 in the binary image after the area filling;

and step 3: performing variable scanning to obtain the volume of the canopy of the fruit tree;

the laser data processing control module (5) respectively controls a first rotating motor (607) and a second rotating motor (611) to be started at a certain rotating speed, and the laser data processing control module (5) respectively sets a left laser sensor (614) and a right laser sensor (605) at different scanning angular speeds S according to the fruit tree canopy porosity K at the left side and the right side_{Laser wheel}Detecting fruit trees on the left side and the right side; the laser data processing control module (5) calculates the volume of the fruit tree canopies on the left side and the right side according to the data collected by the left laser sensor (614), the right laser sensor (605), the first angle sensor (612) and the second angle sensor (610) through the following formula:

y＝f(x)；

ph＝(L_i+R)×sinσ；

in the formula (I), the compound is shown in the specification,

x is the position information of the laser boundary point obtained by each scanning;

y is the fitted contour curve of the canopy after each scan;

L_ithe length of the laser beam that reaches the crown surface;

ph is a vertical projection taking the position of the angle sensor as a starting point and taking the surface of the crown hit by the laser beam as an end point;

r is the radius of the laser wheel;

sigma is a scanning angle in the circumferential motion of the laser sensor acquired by the angle sensor;

H_maxvertical projection at the highest laser point;

H_minvertical projection at the lowest laser point;

v is the volume of the fruit tree canopy;

and 4, step 4: making a decision on spraying;

the laser data processing control module respectively compares the left and right detected volumes of the fruit tree canopies with a preset standard spraying decision value, when the volumes of the fruit tree canopies are smaller than the standard spraying decision value, the spraying operation is not selected, and the spraying machine is started to be arranged in front until the next fruit tree position; when the volume of the fruit tree canopy is larger than or equal to the standard spraying decision value, selecting to carry out spraying operation, and continuing the next step;

and 5: acquiring the air quantity and the spraying quantity required by spraying and the spraying height and the swing angle range of a spray head;

the spraying control module (27) transmits the working speed S of the machine tool according to the speed sensor (29)_{Spraying machine}And the spacing distance between the laser sensor and the spray head, and calculating the spray delay time; after the delay time, the spraying control module (27) controls the pesticide applying device to start working; the spraying control module (27) calculates the air quantity and the spraying quantity required by spraying and the spraying height and the swinging angle range of the spray head according to the volumes of the fruit tree canopies on the left side and the right side by the following formulas:

H＝(L_i1+L_in+2R)×sinσ；

L₀＝(L_i+R)cosσ；

L_i'＝L_{line of}/2；

L＝L_i′-L₀；

W＝P2+V；

Q＝V*q；

Swing angle range: [ σ 1, σ 2 ];

in the formula (I), the compound is shown in the specification,

sigma is the real-time rotating angle of the laser sensor acquired by the angle sensor;

r is the radius of the laser wheel;

L_i1the length of the laser beam at the highest position of the surface of the canopy detected by the laser;

L_inthe length of the laser beam at the lowest position of the surface of the canopy detected by the laser;

h is the height of the crown;

L_{line of}Is the planting row spacing;

L_ithe length of the laser beam when the laser reaches the surface of the crown layer;

L₀a horizontal projection connecting the center of the laser wheel and the length of the laser beam reaching the surface of the canopy;

L_i' is the distance from the center of the laser wheel to the center of the trunk;

l is the distance from the surface of the canopy to the center of the trunk;

p2 is the space volume of the sprayer before the distance from the fruit tree;

v is the volume of the fruit tree canopy;

w is the required air volume;

q is the required spray amount;

h is the spraying height of the spray head;

q is the amount of drug to be administered per unit volume.

10. The method of claim 9, wherein:

in the step 2, the image data processing control module (2) converts the void ratio calculation result into a digital signal through signal processing, then carries out canopy sparsity grading processing, and sends the processing result to the laser data processing control module (5); the digital signals of the calculation results of the void ratio are sequentially divided into three canopy sparsity levels of relatively sparse K1, medium K2 and relatively dense K3, the larger the K value of the void ratio is, the more sparse the canopy is, and K1 is more than K2 is more than K3;

in the step 3, three different laser sensor scanning angular velocities s1, s2 and s3 are respectively set corresponding to three crown layer sparsity levels of sparsity K1, medium K2 and dense K3, and s1< s2< s3 so as to adapt to volume detection at different crown layer sparsity degrees.

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